Problem: $ A = \left[\begin{array}{rrr}0 & 0 & 2 \\ 1 & 1 & 1 \\ 1 & 2 & 0\end{array}\right]$ What is $ A^{-1}$ ?
Explanation: $ = \left[\begin{array}{rrr}-1 & 2 & -1 \\ \frac{1}{2} & -1 & 1 \\ \frac{1}{2} & 0 & 0\end{array}\right]$